AMD is a degenerative eye disease in which the light-sensitive cells in the back of the eye, an area called the macula, stop working. It is the leading cause of severe vision loss in people over age 60.

The disease is divided into two types: "wet" AMD and "dry" AMD.

In dry AMD, patients get deposits in the macula called drusen. Dry AMD is the more common of the two types of AMD; it can lead to wet AMD.

In wet AMD, there is a growth of abnormal blood vessels underneath the macula; the blood vessels leak into the retina.

Researchers found that older adults who had an active lifestyle and exercised three or more times a week had a 70% lower risk of developing wet AMD.

Exercise vs. AMD

In the study, researchers followed nearly 4,000 men and women in Beaver Dam, Wis., between the ages of 43 and 86 for 15 years. The participants were asked about their lifestyle and exercise habits and had detailed eye examinations every five years.

The results, published in the British Journal of Opthalmology, showed that one in four had an active lifestyle and engaged in physical activity strenuous enough to work up a sweat three or more times per week.

After taking other risk factors for age-related macular degeneration into account, including weight, cholesterol levels, and age, researchers found those with an active lifestyle were 70% less likely to develop wet AMD than those who had a sedentary lifestyle.

The risk of age-related macular degeneration also was also 30% lower among people who walked more than 12 blocks regularly.

Researcher M.D. Knudston of the University of Wisconsin School of Medicine and Public Health says other factors, such as diet, may also affect the risk of age-related macular degeneration. But physical activity is known to reduce the type of inflammation and irregularities in the blood vessel walls associated with the wet form of the disease.

In addition, people who lead an active lifestyle may be "biologically" younger than those who are sedentary, which may also reduce their risk of wet AMD because it is a disease associated with agingaging.